Untargeted metabolomics identifies enterobiome metabolites and putative uremic toxins as substrates of organic anion transporter 1 (Oat1)

J Proteome Res. 2011 Jun 3;10(6):2842-51. doi: 10.1021/pr200093w. Epub 2011 Apr 22.


Untargeted metabolomics on the plasma and urine from wild-type and organic anion transporter-1 (Oat1/Slc22a6) knockout mice identified a number of physiologically important metabolites, including several not previously linked to Oat1-mediated transport. Several, such as indoxyl sulfate, derive from Phase II metabolism of enteric gut precursors and accumulate in chronic kidney disease (CKD). Other compounds included vitamins (pantothenic acid, 4-pyridoxic acid), urate, and metabolites in the tryptophan and nucleoside pathways. Three metabolites, indoxyl sulfate, kynurenine, and xanthurenic acid, were elevated in the plasma and interacted strongly and directly with Oat1 in vitro with IC50 of 18, 12, and 50 μM, respectively. A pharmacophore model based on several identified Oat1 substrates was used to screen the NCI database and candidate compounds interacting with Oat1 were validated in an in vitro assay. Together, the data suggest a complex, previously unidentified remote communication between the gut microbiome, Phase II metabolism in the liver, and elimination via Oats of the kidney, as well as indicating the importance of Oat1 in the handling of endogenous toxins associated with renal failure and uremia. The possibility that some of the compounds identified may be part of a larger remote sensing and signaling pathway is also discussed.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Membrane Permeability
  • Fluorescent Dyes
  • Indican / blood
  • Kynurenine / metabolism
  • Metabolome*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Models, Biological
  • Oocytes / metabolism
  • Organic Anion Transport Protein 1 / antagonists & inhibitors
  • Organic Anion Transport Protein 1 / metabolism*
  • Pantothenic Acid / blood
  • Pyridoxic Acid / blood
  • Sulfuric Acid Esters / blood
  • Uremia / blood*
  • Uremia / urine*
  • Urinalysis
  • Xanthurenates / metabolism
  • Xanthurenates / urine
  • Xenopus


  • Fluorescent Dyes
  • Organic Anion Transport Protein 1
  • Slc22a6 protein, mouse
  • Sulfuric Acid Esters
  • Xanthurenates
  • Pantothenic Acid
  • Kynurenine
  • xanthurenic acid
  • Pyridoxic Acid
  • Indican